Overview
The specific objective of this proposed research is to understand whether deficits in sleep-dependent memory changes reflect age-related changes in sleep, memory, or both. The central hypothesis is that changes in both memory and sleep contribute to age-related changes in sleep-dependent memory processing. To this end, the investigators will investigate changes in learning following intervals of sleep (overnight and nap) and wake in young and older adults.
Description
Exp 1: Using neuroimaging, the investigators will consider whether differences in brain areas engaged during memory encoding contribute to age-related changes in sleep-dependent memory consolidation for a word-pair learning task.
Exp 2: The investigators will examine the rate of memory decay between encoding and sleep using two probes of declarative memory (word-pair learning and visuo-spatial learning).
Exp 3: The investigators will provide additional opportunity for encoding of the word-pair and visuo-spatial learning tasks.
Exp 4: Using neuroimaging, the investigators will examine neural engagement during encoding and performance following intervals of sleep and wake.
Exp 5: The investigators will examine the rate of decay of motor sequence learning.
Exp 6: The investigators will examine whether enhanced training ('overtraining') improves sleep-dependent memory consolidation for older adults.
Eligibility
Inclusion Criteria:
- Age 18-80 yrs
- Healthy sleeper
- No diagnosed sleep or neurodegenerative disorder
Exclusion Criteria:
- Past diagnosis of any sleep disorder or evidence of a sleep disorder as assessed by self-reported sleep quality assessments, a standardized diagnostic interview, and an acclimation night of polysomnography. Using acclimation-night polysomnography, participants will be excluded with an Apnea-Hypopnea Index \>15; a Period-Limb Movement in Sleep index of \>15/hr; sleep-onset latency \> 45 min (indicative of insomnia); or sleep efficiency \< 80% (see Edinger et al., Sleep, 2004). In cases in which questions arise regarding a participants' inclusion or sleep records, a practicing neurologist board-certified in sleep medicine will review the documentation.
- Past diagnosis neurological illness or head injury
- Reported average sleep per night \< 5 or \> 9 hrs
- Current employment involving shift work or an inability to keep a regular sleep schedule during the week prior to testing
- Current use of psychotropic, recreational drugs, or sleep-altering medications (sleep medications, cold medicines within the past week, clonidine, sympathomimetic stimulants)
- Daily caffeine intake of \> 4 cups (coffee, tea, colas)
- Weekly alcohol intake of \> 10 cups
- Pregnancy or \< 12 months post-partum
- History of bipolar disorder, mania, or current evidence of depression as measured by Beck Depression Inventory score \> 25
- Abnormal sleep (e.g., shift work, travel across \>2 time zones within the past 3 months).
- Diagnosis of any Axis I disorder, neurological illness or head injury (according to Demographic and Health History form);
- Score indicative of cognitive dysfunction (subtest scores \< 40)
- Beck Depression Scale score indicative of depression (\> 19).
Additionally, individuals will be excluded from magnetic resonance imaging studies (Exps 1, 4) for:
- Left handed or ambidextrous
- Claustrophobia
- Presence of metal (thoroughly screened via questionnaire and metal detector)
- Pregnancy
